FOOD PROCESSING Flashcards
WHY PROCESS FOODS?
- EXTEND SHELF LIFE
- MAINTAIN SENSORY PROPERTIES
- MAINTAIN OR IMPROVE NUTRITIVE PROPERTIES
- ENSURE SAFETY
- MAKE MORE CONVENIENT
- BOTTOM LINE: $$ (ECONOMIC VALUE)
HEAT PROCESSING
Use of high temperatures to destroy enzymes
and microorganisms that could reduce quality and/or safety of food
What type of HEAT PROCESSING
BLANCHING
PASTEURIZATION
COMMERCIAL STERILIZATION
STERILIZATION
A mild heat treatment that primarily destroys
enzymes and reduces microbial load (does not necessarily kill pathogens), further preservation methods needed to extend shelf life.
BLANCHING
A mild heat treatment used primarily to destroy pathogenic organisms but it also destroys enzymes and reduces microbial load.
PASTEURIZATION
Example of BLANCHING
Vegetables, frozen, canned
PASTEURIZATION
Requires an addition preservation method to extend shelf life example
refrigeration, drying
STERILIZATION
- A very severe heat treatment that destroys all microorganisms.
A severe heat treatment that destroys pathogenic and many microorganisms that could spoil food.
COMMERCIAL STERILIZATION
COMMERCIAL STERILIZATION Extends shelf life, room temperature stable example
.canned foods
METHODS OF HEAT TRANSFER
CONDUCTION
CONVECTION
RADIATION
Heating of solids; Slow heating; Heating of fixed molecules in a row.
CONDUCTION
CONDUCTION Examples
spoon in sauce pan.
Solid pack pumpkin in a can.
Faster heating of liquids and gas; Hot liquids and gasses raise, cooler portions sink, creating a flow or
current.
CONVECTION
Examples of CONVECTION
forced air heating in houses; Canned juices.
Electromagnetic
waves.
RADIATION
RADIATION Two general types:
1- Heat radiation from a heat source.
2- No heat radiation that causes the food to heat up.
No heat radiation that causes the food to heat up
such as
1- Microwaves
2- Irradiation that does not transfer heat: Gamma
rays, x-rays, electrons (E-beam), Ultraviolet).
Heat radiation from a heat source.
Flames:
campfire, hot dogs, hamburgers, BBQ.
Infrared.
FACTORS INFLUENCING CHOICE OF HEAT TREATMENTS
- Type of food
- Level of contamination
- Presence of oxygen
- Heat resistance of organisms or enzymes
- Heat penetration
- Packaging material
- Size of container
- Sensory qualities desired
In medium & low acid (>4.5 pH) Foods, the canning process is designed to kill
C.Botulinum.
Low acid
5.0 - 6.8.
Meat, dairy, vegetables
Medium acid
4.6 - 5.0.
Soups, vegetables
Acid
3.7 - 4.5.
Fruits
High acid
2.3 - 3.6
Citrus fruits, berries
OBJECTIVES BLANCHING OF FRUITS AND VEGETABLES
- Inactivate enzymes
- Lower microbial load (combination of rinsing action and heat)
- Aids in packaging – wilts vegetables and removes respiratory
gases - Removes dirt, leaves, etc.
- Aids in peeling
Inactivate enzymes
A. Metabolic B. Maintain color C. Texture D. Flavor
E. Nutritive value
GREEN BEANS: Become mushy upon high heat treatment. Therefore, one way to keep them firmer is to
activate Pectin Methyl Esterase (PME)
DRY BEANS: Must be partly rehydrated before
blanching
ADEQUACY OF BLANCHING:
Enzyme tests: • Peroxidase • Catalase • Lipoxygenase Physical: • Wilting • Color
PASTEURIZATION Used for
milk, liquid eggs, fruit juices
and beer.
Function of PASTEURIZATION
Destroy pathogens
Reduce microbial load
Inactivate enzymes
Extend shelf life
Low-Temperature Long-Time
pasteurization (Vat):
145° F (62.8° C) for
30 minutes
High-temperature short-
time (HTST) :
161° F (71.7° C) for 15
seconds
• 191° F (88.3° C) for 1 second • 194° F (90° C) for 0.5 second
Ultra-high temperature (UHT):
275-284° F (135 to 140° C) for a few seconds
CREAM
150-155° F (65.6-68.3° C) For 30 minutes
166-175° F(74.4-79.4° C) For 15 seconds
EGG PASTEURIZATION: Based upon
killing and preventing growth of salmonella
MILK PASTEURIZATION: Based upon
T.B. Microorganism
Liquid eggs PASTEURIZATION heated to
140-144° F(60-62° C) and held for 3.5-4.0 minutes
